Я хочу напомнить пользователю, когда он выбрал какую-то дату. Я нашел пример для остаткаВот но я получилNullPointerException.

package com.example.eventremainder;

import java.util.Calendar;

import com.example.eventremainder.R;
import com.example.eventremainder.Service.ScheduleClient;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.provider.Contacts;
import android.provider.ContactsContract;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

public class AddEventActivity extends Activity{
    private EditText nameEditText,phoneet;
    TextView dobm;
    private DatePicker datePicker;
    private Button ok,browse;
    private String checkedevent;
    private Spinner spinner;
    private ScheduleClient scheduleClient;
    private static final String[] arrayString={"BirthDay","MarriageDay"};
     public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.selectevent);
            nameEditText=(EditText)findViewById(R.id.editText1);
            phoneet=(EditText)findViewById(R.id.phneno);
            dobm=(TextView)findViewById(R.id.dobm);
            datePicker=(DatePicker)findViewById(R.id.scheduleTimePicker);
            spinner=(Spinner)findViewById(R.id.spinner1);
            ok=(Button)findViewById(R.id.ok);
            browse=(Button)findViewById(R.id.browse);
            ok.setEnabled(false);
            scheduleClient=new ScheduleClient(AddEventActivity.this);
            scheduleClient.doBindService();
      }

    public void onResume()
    {
        super.onResume();
        nameEditText.addTextChangedListener(tw);
        dialogBox();
    }
    TextWatcher tw=new TextWatcher() {
        public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
            if(String.valueOf(arg0).equals(""))
            {
                ok.setEnabled(false);
            }
            else{
                ok.setEnabled(true);
            }
        }
        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
        }
        public void afterTextChanged(Editable arg0) {
            if(!nameEditText.getText().toString().equals("")){
                ok.setEnabled(true);
            }
        }
    };
     public void dialogBox()
      {
            ArrayAdapter<String > arrayAdapter=new ArrayAdapter<String>(AddEventActivity.this, android.R.layout.simple_dropdown_item_1line, arrayString);
            spinner.setAdapter(arrayAdapter);
            spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
          public void onItemSelected(AdapterView<?> arg0, View arg1,
                        int arg2, long arg3) {
                    checkedevent=arrayString[arg2];
                }
                public void onNothingSelected(AdapterView<?> arg0) {
                }
            });

            browse.setClickable(true);
            ok.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {
                    SQLiteDatabase sqLiteDatabase=null;
                    sqLiteDatabase=openOrCreateDatabase("eventremainder", 0 ,null);
                    String checkedname="---";
                    String phone="--";
                    int day=0,month=0,year;
                    checkedname=nameEditText.getText().toString().trim();
                    day=datePicker.getDayOfMonth();
                    year=datePicker.getYear();
                    month=datePicker.getMonth();
                    String month2=month(month);
                    String date=""+day+"-"+(month2);
                    Calendar c=Calendar.getInstance();
                    c.set(year, month, day);
                    c.set(Calendar.HOUR_OF_DAY, 0);
                    c.set(Calendar.MINUTE, 0);
                    c.set(Calendar.SECOND, 0);
                    // Ask our service to set an alarm for that date, this activity talks to the client that talks to the service
                    scheduleClient.setAlarmForNotification(c);
                    try{
                    String selection="name=? and event=? and day=? and month=?";
                    String[] whereArgs1={checkedname,checkedevent,""+day,month2};
                    Cursor cursor=sqLiteDatabase.query("eventstable", null, selection, whereArgs1, null, null, null);
                    if(cursor.moveToNext())
                    {
                        throw new IndexOutOfBoundsException();
                    }
                    else
                    {
                    ContentValues cv=new ContentValues();
                    cv.put("name", checkedname);
                    cv.put("event", checkedevent);
                    cv.put("day",day);
                    cv.put("month", month2);
                    cv.put("monthint", month);
                    cv.put("year", year);
                    cv.put("phone_no",phone);
                    nameEditText.setText("");
                    phoneet.setText("");
                    long l=sqLiteDatabase.insert("eventstable", null, cv);
                    if(l!=-1l)
                    {

                        Toast.makeText(getApplicationContext(), checkedname  +  checkedevent  + " Added " , Toast.LENGTH_LONG).show();
                        switchToTab(checkedevent);
                    }
                    }
                    }
                    catch (IndexOutOfBoundsException e) {
                        nameEditText.setError("These Details are already exists");
                    }
                    finally{
                        sqLiteDatabase.close();
                    }
                }
            });

      }

     public String month(int month)
    {
        String month1=null;
        switch (month) {
        case 0:month1="Jan";
            break;
        case 1:month1="Feb";
        break;
        case 2:month1="Mar";
        break;
        case 3:month1="Apr";
        break;
        case 4:month1="May";
        break;
        case 5:month1="Jun";
        break;
        case 6:month1="Jul";
        break;
        case 7:month1="Aug";
        break;
        case 8:month1="Sep";
        break;
        case 9:month1="Oct";
        break;
        case 10:month1="Nov";
        break;
        case 11:month1="Dec";
        break;

        }
        return month1;
    }
     public void browsemethod(View arg0)     {

         Intent intent =new Intent(getApplicationContext(), ContactsListActivity.class);
         startActivityForResult(intent, 1);
     }
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
          super.onActivityResult(requestCode, resultCode, data);
          if(resultCode==RESULT_OK && requestCode==1){
           String name  = data.getStringExtra("name");
           String phone=data.getStringExtra("phonenumber");
           tw.onTextChanged(name, 5, 5, 5);
               nameEditText.setText(name);

               phoneet.setText(phone);
          }
    }
     public boolean onKeyDown(int keyCode,KeyEvent event)
     {
         super.onKeyDown(keyCode, event);
         switch (keyCode) {
        case KeyEvent.KEYCODE_BACK:
            AlertDialog.Builder alertdialogbuilder=new AlertDialog.Builder(AddEventActivity.this);
            alertdialogbuilder.setTitle("Do you want to exist from application");
            alertdialogbuilder.setPositiveButton("yes", new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
                    finish();
                }
            });
            alertdialogbuilder.setNegativeButton("No", new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {


                }
            });
            alertdialogbuilder.create();
            alertdialogbuilder.show();
            return true;

        default:
            break;
        }
        return false;

     }
     public void switchToTab(String tab)
     {
         TabMainActivity tabMainActivity=(TabMainActivity) this.getParent();
                 if(tab.equalsIgnoreCase("BirthDay"))
             {


                     tabMainActivity.switchTab(0);
             }
         else {
             if(tab.equalsIgnoreCase("MarriageDay"))
             {
                 tabMainActivity.switchTab(1);

             }
         }

     }
}
</b>



another class i ussed is scheduleclient 
<b>
package com.example.eventremainder.Service;

import java.util.Calendar;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;

/**
 * This is our service client, it is the 'middle-man' between the
 * service and any activity that wants to connect to the service
 * 
 * @author paul.blundell
 */
public class ScheduleClient {

    // The hook into our service
    private ScheduleService mBoundService;
    // The context to start the service in
    private Context mContext;
    // A flag if we are connected to the service or not
    private boolean mIsBound;

    public ScheduleClient(Context context) {
        mContext = context;
    }

    /**
     * Call this to connect your activity to your service
     */
    public void doBindService() {
        // Establish a connection with our service
        mContext.bindService(new Intent(mContext, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
        mIsBound = true;
    }

    /**
     * When you attempt to connect to the service, this connection will be called with the result.
     * If we have successfully connected we instantiate our service object so that we can call methods on it.
     */
    private ServiceConnection mConnection = new ServiceConnection() {
        public void onServiceConnected(ComponentName className, IBinder service) {
            // This is called when the connection with our service has been established, 
            // giving us the service object we can use to interact with our service.

            mBoundService = ((ScheduleService.ServiceBinder) service).getService();
        }

        public void onServiceDisconnected(ComponentName className) {
            mBoundService = null;
        }
    };

    /**
     * Tell our service to set an alarm for the given date
     * @param c a date to set the notification for
     */
    public void setAlarmForNotification(Calendar c){
        mBoundService.setAlarm(c);
    }

    /**
     * When you have finished with the service call this method to stop it 
     * releasing your connection and resources
     */
    public void doUnbindService() {
        if (mIsBound) {
            // Detach our existing connection.
            mContext.unbindService(mConnection);
            mIsBound = false;
        }
    }
}

Было показано исключение нулевого указателя вmBoundService.setAlarm(c).